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1995 Mustang GT- Thorough Coolant Flush

23K views 11 replies 4 participants last post by  Urambo Tauro 
#1 ·
1995 Mustang GT, 135000 miles

I'm getting ready to do a coolant flush here, and want to do a thorough job on it. Any tips for getting all the sediment and stuff out?

I'd like to get the radiator, block, heater core-- everything flushed.

I was thinking about draining the coolant, then running water into the top of the radiator with the drain open while running the engine (heater on full hot setting). Is this a good idea? Should I remove the thermostat temporarily to accomlish this?
 
#2 ·
I did a flush not to long ago. All you need for a flush is just the fluid itself from autozone. I suggest changing the thermostat while your at it. If you live in a hot state like Texas or Az than I suggest asking for a lower temp thermostat than normal like 170*.

First: Remove the thermostat ( if you do buy a new one).
Second: Drian all of the fluid ( drain will be located on bottom left or right of radiator, its just a little plastic bolt).
Third: Cap the drains, replace your thermostat and fill the radiator with the suggested or correct amount of radiator flush.
Fourth: Fill the remainder of the radiator with water all the way up to the fill line.
Fifth: Start the engine and let it run for 10-20 min.
Sixth: Drain the water same way as coolant.
Seventh: Fill the radiator with just water to the fill line, than start the engine and let it run for 10 min. Repeat this step another 2 or 3 times to get all of the flush out.
Eight: Drain what is left of the water, than close the drain.
Nine: Fill your radiator with 50/50, coolant/water and your done!


I did that same process and my engine ran like a champ and was as cool as ever!

Note: If you do replace the thermostat, also be sure to buy a thermostat o-ring gasket. When you replace the thermostat, make sure you have that o-ring fitted correctly. Just keep a close eye during your flushes with the hood open for any leaks around the thermostat housing.

Good luck m8 :bigthumbsup
 
#3 ·
After using the flush, running straight water through it, I'm thinking about removing the thermostat so everything can flow freely for the next couple of dainings before I start putting coolant back in. At which point, I'll take the opportunity to put a new thermostat in.

But, how much water is going to remain in the system once I'm ready for the final refill? If I just refill with 50/50, I'll actually wind up with more water than coolant, right?
 
#4 ·
Autozone sells a 50/50 coolant. As long as you top it off with that than you will have a perfect 50/50. You want that half and half though, no more no less. When you refill with 50/50 though, drain all of the water from the flush. You want all of it out.

Good idea with the thermostat. I wouldnt replace it till your done with the flush, otherwise theres a chance the thermostat would never opun, thus the flush would not reach the block.
 
#5 ·
So you're saying the radiator drain is the low point for the entire system? It will drain the block, heater core, everything?

I have been under the assumption any mix that contains 50-70% coolant is acceptable. What happens if I go too much or too little either way?
 
#6 ·
Ya, the drain on the radiator drains pretty much all of it out. It will drain the block and heater core.

If a mix does contain a little more coolant, thats ok. You just dont want any more than 75% coolant. Too much coolant can yield bad effects on a daily driven car. Track cars use 100% coolant to really keep the temp down. And be sure to have alteast 40% coolant in the radiator, no less.
 
#10 ·
Yeah, I'm saving my distilled water for the final fill. I'll use tap water only for the flushings.

Okay, I had assumed some stayed in the system because of a flush I just did on my MN12 Cougar. The Chilton book told me the capacity was 3 gallons, so I poured in 1-1/2 gallons of coolant. I then added the water, but it filled up fast. Even after running it through the system, and doing the final top-off, I still had only used almost a gallon of water. I figured some water from the last flush hadn't drained.

Maybe since I had the front jacked up, it hadn't drained all the way because it wasn't level? Or does the 3gal capacity include the expansion tank filled to the brim, well past the hot line? I notice my 95's capacity is rated at 3-1/2 gallons.
 
#9 ·
Draining the radiator will not get close to all the water out.
You want to do the flush so that all that is in the engine at the end of the process is pure water. Drain out what you can, then add half the cooling system capacity worth of pure coolant, and top off with water.... this will give you a 50/50 mix, plus then you don't have to waste your money on coolant that is 50% water.

I believe that these take a little under 4 gallons total, so 1.5-2 gallons of pure coolant should do the job.
 
#12 ·
Whoops, missed your post there, 5.0Mustang1989. You slid it in before I finished typing.
Yeah, like I said, that's what I experienced on my MN12, so I thought the SN95 might do the same. Any idea how much water will be in there? I'll just put the coolant in first, like last time & as you said.
 
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